Mobile phones, such as cellular phones, are ubiquitous in society. In most countries, mobile phones outnumber land-line phones, with fixed landlines numbering 1.3 billion but mobile subscriptions 3.3 Billion at the end of 2007. Mobile phone usage is a key means by which people communicate with each other. Use of mobile phones, however, has led to associated annoyance at mobile phone conversation noise and has led to concern regarding security of conversations.
Mobile phone use can be an important matter of social discourtesy: unwanted one-sided conversations in public areas, phones ringing during funerals or weddings, in cinemas, and theatres. Some public places such as bookstores, libraries, bathrooms, cinemas, doctors' offices, and places of worship where silence or quiet is desired prohibit the use of mobile phones, so that other patrons will not be disturbed by conversations. Mobile phone usage on local public transport is also increasingly seen as a nuisance. Some cities, thus, have mandated a total ban of mobile phones on public transportation. Some transportation providers, particularly those involving long-distance services, offer a quiet carriage where phone use is prohibited, much like the designated non-smoking carriage of the past. It is common, however, for users to ignore such bans and designations.
Mobile phone usage and the perceived annoyance of others to a user's mobile phone use has led to various facilities and establishments exploring methods to force non-use of mobile phones. For example, some facilities install signal-jamming equipment to prevent their use. However, in many countries, including the United States, such equipment is illegal. Accordingly, some public places, such as auditoriums, in the United States, have installed wire mesh in the walls to make a Faraday cage, which prevents signal penetration without violating signal jamming laws.
A related issue is the increased use of phones in public places where a user of a mobile phone may be concerned about others overhearing portions of his conversation.
The issue of mobile communication and etiquette has also become an issue of academic interest. The rapid adoption of the device has resulted in the intrusion of telephony into situations where this was previously not known. This has exposed the implicit rules of courtesy and opened them to reevaluation.